This invention relates to the treatment of whole blood to inactivate or destroy infective viruses found in animal fluids and cells, such as the cytomegalovirus which is responsible for or aggravates serious and sometimes fatal infections, in blood transfusion recipients. The term "inactivate" as applied to the inactivation of virus in accordance with the present invention means that the virus are rendered non-infectious to the patient. In some instances, virus cultures may still be viable for a period of time, but lack the ability to pathogenically infect a patient.
Cytomegalovirus (CMV) is probably the most ubiquitous of the pathogenic viruses found in animal fluids and tissues. Virtually all of the people living in the developing countries become infected with CMV early in life, and CMV infects over half the population in the developed countries of the world. CMV may remain essentially inactive in the body following an initial infection and may flare in to an active infection any time, most frequently when the body's immune system is compromised to a greater or lesser degree by disease, radiation therapy, drug therapy, surgical trauma, etc. CMV is frequently associated with, and may be a causative or contributing factor in, lifethreatening disease in individuals with suppressed immune systems, and can be a principal causative factor in pneumonia, neurological disorders, febrile illness, ocular disease and hepatitis. CMV infection is a serious limiting factor in the transplantation of organs, tissues and cells and the transfusion of blood and plasma from one individual to another. The kidney transplant patient runs a high risk of contracting serious, and not infrequently fatal, CMV infection from CMV introduced by the transplant organ. Recipients of whole blood, plasma, bone marrow, cornea, cardiac, and semen run a serious risk of CMV infectious disease, the risk being multiplied where the immune system of the recipient is suppressed to prevent rejection of the foreign organ or cells, or where immunosuppression is present from natural causes.
CMV is frequently associated with Pneumoncystis carinii and may cause or contribute to encephalitis and colitis and may be associated with Kaposi's sarcoma in AIDS patients. CMV is so ubiquitous in the blood and organs of donors who, frequently, exhibit no symptoms of infection, and its direct and contributory effects in infectious diseases is so pervasive and subtle that a CMV infection is to be presumed if another causative agent cannot be established.
There are no proven cures or generally effective drugs for the treatment of CMV infections. Certain drugs, e.g. ganciclovir, has been shown to have limited effectiveness in the treatment of certain CMV infections, e.g. CMV retinitis, but has little effect in the treatment of CMV pneumonia. Live attenuated CMV vaccine has been developed but may not protect against infection by natural CMV, and there is a real risk that the attenuated CMV may reactivate during pregnancy and infect the fetus.
While a method of preventing, or even reducing the likelihood of transmitting CMV via transfusion or transplant of organs, tissues, cells or fluids would be of enormous benefit to medical science, the present invention is not limited to treatments to inhibit CMV infection and is applicable to other classes of viruses found in animal fluids and tissues.
CMV is a member of the human herpesvirus (HV) group, which are responsible for much of mankind's discomfort and pain. The herpesviruses represent a very large, clearly defined group of viruses which are responsible for, or involved in, cold sores, shingles, a venereal disease, mononucleosis, eye infections, birth defects and probably several cancers. Three subfamilies are of particular importance. The alpha subfamily includes HV-1 (herpes virus simplex 1) which causes cold sores, fever blisters, eye and brain infections, HV-2 (herpes virus simplex 2) which cause genital ulceration, and HV-3 (HV varicella zoster) which causes chicken pox, shingles and brain infections. The beta subfamily includes HV-5, the principal member of which is CMV discussed above. The gamma subfamily includes HV-4 (Epstein-Barr) which cause infectious mononucleosis and is involved in Burkitt's lymphoma and nasopharyngeal carcinoma. Additional possibly pathogenic herpes viruses no doubt exist, one type of which, HV-6, of unknown pathogenicity has been identified. (Niederman, J. C. et al., The Lancet, Oct. 8, 1988, 817). There is evidence that the methods of this invention are effective in inhibiting the transmission of infections caused by many and perhaps all of the pathogenic herpes viruses found in animal fluids and tissues.
While blood bankers have instituted rigid criteria for exclusion of potential donors in high risk categories, this is not a satisfactory solution to the most significant threat to face the health care community in many decades. Institution of human immunodeficiency virus (HIV) testing has blood products safer, but the complete elimination of HIV contaminated blood and blood products has not been possible using present knowledge and technology. The ELISA test, for example, misses approximately 1 in 200 (0.5%) HIV infected donors, and there is no certain method for excluding donor carriers of hepatitis and other infectious viruses found in animal fluids and tissues. Increasing efforts are exerted to improve the safety of the blood supply such as retrovirus screening using surrogate markers, screening for HIV and other retroviruses with attention to population surveillance for newer agents, cleaner methods of extracting specific blood components by monoclonal antibody techniques and DNA methodologies, development of recombinant DNA products which by-pass the need for plasma derived clotting factors for administration to hemophiliacs. Careful screening of donors, followed by antibody testing, reduces the risk of AIDS and other virus-contaminated blood, but such methods are not foolproof. Such methods require testing supplies and trained technicians which are not available and are too expensive for use in such places as central Africa and other third-world countries where AIDS infects up to onethird of the population. A simpler and less costly method of handling blood is required in such areas of the world.
A photodynamic method has also been evaluated as a means of eradicating viral contaminants (Matthews, J. L. et al., Transfusion, 28,1 1988) but has not been proved to be generally effective and safe. While Factor VIII products may be rendered non-infectious by heat or solvent-detergent methods, no methods are known to guarantee the safety of whole blood or cellular components or plasma. For the whole blood recipient, however, the only reasonably reliable safety procedures are programs allowing for self donation prior to elective surgery by the donor and the use of blood from designated donors, but such programs are incredibly difficult logistically. In spite of heroic efforts to meet the challenge of virus contaminated blood supply, an imperative need continues to exist for a method for treating whole blood for use in transfusion.
It is apparent from the foregoing discussion that a method of killing or inactivating pathogenic viruses in organs, tissues, cell and fluids intended for transfusion or transplantation would be an enormous advance in medicine. It is to this major national and worldwide health care challenge that the present invention is directed.
My copending U.S. patent application Ser. No. 07/290,161, Filed Dec. 28, 1988, describes and claims a method for inactivating virus in blood samples using glycyrrhizic triterpenoid compounds.
The invention described and claimed herein is an improvement thereof and is based upon the discovery of unique synergistic improvement results when glycerol, even trace amounts of glycerol, are combined in the blood or blood product sample with glycyrrhizic triterpenoid compounds.
Further, the invention described and claimed herein is an improvement thereof and is further based upon the discovery of unique synergistic improvement results when even trace amounts of ethylene diamine tetraacetic acid or salts thereof (EDTA), are combined in the blood or blood product sample with glycyrrhizic triterpenoid compounds.